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Differential D12433

rust-hgpath: add `repr(transparent)` to `HgPath`
ClosedPublic

Authored by Alphare on Apr 4 2022, 11:30 AM.

Details

Reviewers
None
Group Reviewers
hg-reviewers
Commits
rHG9dcfd1d05e6e: rust-hgpath: add `repr(transparent)` to `HgPath`
rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath`
Summary

It's been stabilized a long time ago, so let's not rely on an implementation
detail now.

Diff Detail

Repository
rHG Mercurial
Branch
stable
Lint
No Linters Available
Unit
No Unit Test Coverage

Event Timeline

Alphare created this revision.Apr 4 2022, 11:30 AM
baymax updated this revision to Diff 32767.Apr 4 2022, 2:34 PM

✅ refresh by Heptapod after a successful CI run (🐙 💚)
⚠ This patch is intended for stable ⚠

Alphare added a commit: rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath`.Apr 4 2022, 4:06 PM
This revision was not accepted when it landed; it landed in state Needs Review.
Closed by commit rHGa79c3c7cee14: rust-hgpath: add `repr(transparent)` to `HgPath` (authored by Alphare). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mrust/hg-core/src/utils/hg_path.rs (9 lines)

Diff 32767

rust/hg-core/src/utils/hg_path.rs

/// operation. /// operation.
/// ///
/// This allows us to be encoding-transparent as much as possible, until really /// This allows us to be encoding-transparent as much as possible, until really
/// needed; `HgPath` can be transformed into a platform-specific path (`OsStr` /// needed; `HgPath` can be transformed into a platform-specific path (`OsStr`
/// or `Path`) whenever more complex operations are needed: /// or `Path`) whenever more complex operations are needed:
/// On Unix, it's just byte-to-byte conversion. On Windows, it has to be /// On Unix, it's just byte-to-byte conversion. On Windows, it has to be
/// decoded from MBCS to WTF-8. If WindowsUTF8Plan is implemented, the source /// decoded from MBCS to WTF-8. If WindowsUTF8Plan is implemented, the source
/// character encoding will be determined on a per-repository basis. /// character encoding will be determined on a per-repository basis.
//
// FIXME: (adapted from a comment in the stdlib)
// `HgPath::new()` current implementation relies on `Slice` being
// layout-compatible with `[u8]`.
// When attribute privacy is implemented, `Slice` should be annotated as
// `#[repr(transparent)]`.
// Anyway, `Slice` representation and layout are considered implementation
// detail, are not documented and must not be relied upon.
#[derive(Eq, Ord, PartialEq, PartialOrd, Hash)] #[derive(Eq, Ord, PartialEq, PartialOrd, Hash)]
#[repr(transparent)]
pub struct HgPath { pub struct HgPath {
inner: [u8], inner: [u8],
} }
impl HgPath { impl HgPath {
pub fn new<S: AsRef<[u8]> + ?Sized>(s: &S) -> &Self { pub fn new<S: AsRef<[u8]> + ?Sized>(s: &S) -> &Self {
unsafe { &*(s.as_ref() as *const [u8] as *const Self) } unsafe { &*(s.as_ref() as *const [u8] as *const Self) }
} }